An organic light emitting device using organic light emission is extensively applied to various types of lighting apparatuses because of an advantage of high brightness obtained using low voltage and also to display devices because of advantages of low voltage driving, light weight and slimness, a wide viewing angle, and a high-speed response.
The organic light emission means that electric energy is converted into light energy by using an organic substance. That is, in the case of when an organic layer is interposed between an anode and a cathode, if voltage is applied between two electrodes, holes are injected into the organic layer at the anode and electrons are injected into the organic layer at the cathode. When the injected holes and electrons meet each other, an exciton is formed. The exciton falls down to a bottom state to emit light.
For example, JP-A-2005-108643 discloses an organic light emitting device that includes a first electrode having a rod shape or a first electrode formed on a surface of a support rod, an organic layer formed on a surface of a first electrode, and a second electrode formed on a surface of the organic layer.
In connection with this, the first electrode is formed around the entire support rod, the organic layer is formed around the entire first electrode, and the second electrode is formed around the entire organic layer.
The organic light emitting device having the above-mentioned structure emits light by injection of a current, the first electrode is formed around the entire support rod, and the second electrode is formed around the entire support rod. That is, the first electrode and the second electrode are formed as a large unit cell around the support rod. Hence, there is a disadvantage in that the quantity of current injected per unit area is large.
In the case of when the first electrode and the second electrode are formed as a large unit cell around the support rod or the first electrode and the second electrode are connected in parallel, it is possible to perform low voltage driving in order to ensure required brightness. However, the quantity of current to be injected is increased. For example, in order to manufacture a device of 10 □/W and ensure 1000 □, power of 100 W is required. If driving is performed by using 5 V, a injection current of 20 A is required.